题目3单选题
设二元函数<img src="https://tihai-oss-cloud.itihey.com/img/99b49fe8c89c404cfc8b04af71539a85.webp">;当<img src="https://tihai-oss-cloud.itihey.com/img/bca64495282358f98d4e3a4846623810.webp">时,<img src="https://tihai-oss-cloud.itihey.com/img/bde2017a5b8333912474a98b9209ba80.webp">,则在点(0,0)处A. 连续,偏导数存在B. 连续,偏导数不存在C. 不连续,偏导数存在D. 不连续,偏导数不存在